Powershell wait for an action

Hello,

i created this PS script

## IdentifyingNumber will be stored in a vraiable

$myApp = “7-z”
$app = Get-WmiObject win32_product | Where-Object {$_.name -match $myApp}

WAIT

$app.IdentifyingNumber
$appIN = $app.IdentifyingNumber

## Unisntallation

start msiexec.exe /X$appIN /qn

Where i put in WAIT the script should be stopped until the Get-Wim command is done.